Additive for Hydrocarbon Fuel and Related Process

ABSTRACT

The present invention relates to the field of fuel additives for hydrocarbon fuels that acts to enhance efficiency and/or reduce pollution. The fuel additive is a phosphorus-containing composition that can be dispersed in hydrocarbon fuels or liquid carriers for combustion with the fuel in a combustion zone.

RELATED APPLICATIONS

This patent application claims priority to U.S. Non-Provisional PatentApplication Ser. No. 10/875,765, filed on Jun. 23, 2004, which claimspriority to U.S. Provisional Patent Application Ser. No. 60/480,701,filed on Jun. 23, 2003, both of which are incorporated by reference intheir entireties.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of fuel additives, inparticular, to an additive for hydrocarbon fuels to enhance efficiencyand/or reduce pollution.

BACKGROUND OF THE INVENTION

Many hydrocarbon fuels have been used, each with their own advantagesand drawbacks. Examples of such fuels include gasoline, natural gas,diesel, kerosene, jet fuel, LPG, heavy distillates, bunker fuel,ethanol, coal, other solid hydrocarbon fuels and the like. Chemicalcompounds have been used as fuel additives over the past century toimprove various parameters, such as octane number, of various fuels. Theuse, and subsequent banning, of lead in gasoline has been known for along time. Tetraethyl lead showed a positive effect on octane and aprofoundly negative effect on the environment.

In addition to tetraethyl lead, several elements are known to havecombustion catalyst characteristics in gasoline or other hydrocarbonfuels. Examples, in addition to lead, are manganese, iron, copper,cerium, calcium and barium. Each of these elements has advantages anddisadvantages in particular applications. Drawbacks of certain ironcompounds include limited solubility in gasoline, toxicity, and expenseas an additive. Interaction with sulfur and creation of sulfideprecipitate may also occur, which is undesirable.

Another commonly-used additive in gasoline is MTBE. While this compoundboosts octane levels significantly, the compound is thought to becarcinogenic. Also, it mixes easily with water which is hazardous shouldthere be a leak. Gasoline containing MTBE leaking from an undergroundtank at a gas station could potentially leach into groundwater andcontaminate wells. As a result of the believed negative potential ofMTBE on the environment, ethanol is also being evaluated as a gasolineadditive to boost octane.

In addition to the industry goal of improved combustion efficiency,smoke emissions reduction is also a concern, particularly for dieselfuel applications. The industry has not made substantial progress ondevelopment of a fuel additive for reducing smoke and particulateemissions

Finally, adjustment of combustion parameters is made to attempt tomaximize function to reduce CO and NOx. In spite of these andcombinations of these attempts to minimize pollutants, fuel combustioncontinues to be a focus of interest to improve fuel efficiency andreduce pollutants.

A fuel additive that includes a combustion catalyst to reduce smoke andparticulate emissions from bus, truck and automobile engines operatingon gasoline fuels would be advantageous. Also advantageous would be afuel additive that increases efficiency and/or decreases pollutants fordiesel fuel applications. It would be advantageous to reduce smoke,particulate and nitrogen emissions from fuel applications. An additivethat does not result in the formation of precipitates would be alsoadvantageous. An additive for hydrocarbon fuel that reduces level of NOxproduced would also be advantageous. Finally, an additive that remainsstable during the combustion process would be advantageous.

SUMMARY OF THE INVENTION

The present invention includes a fuel additive and a method of using theadditive in relation to hydrocarbon fuel.

The fuel additive of the invention includes a phosphorus-containingparent solution containing [Y]_(x)H₂PO₄, [Y]_(x+1)HPO4,where Y is acation. Y does not have to be the same cation in both salt compounds.The cationic portion of the salt components can be any cation, withpotassium being a preferred cation. In this case, the preferredcomponents would be KH₂PO₄, K₂HPO₄. These salts are at least partiallydispersed in water or other appropriate solvent to create thephosphorus-containing parent solution. Advantageously, this embodimentof the fuel additive is an ammonia-free solution. One preferredembodiment includes adding these components in the presence of water tocreate the phosphorus-containing parent solution as an aqueous parentsolution. The water acts as the solvent. Other preferred solventsinclude hydrocarbons or alcohols.[[.]] Another group of preferredcations would be the alkali metals or Group 1A. While NH₄ used as Ycreates a fuel additive that enhances fuel performance, there areinstances when it is preferred to avoid ammonium and thereby ammoniaaltogether.

The phosphorus-containing parent solution is added or mixed with acarrier fluid. The carrier fluid is a fluid that is operable to maintainthe salts within the carrier fluid in at least a partially dispersedstate and that is miscible, or capable of being maintained in solution,in the hydrocarbon fuel. In a preferred embodiment, the solvent islargely removed from the phosphorus-containing parent solution withcarrier fluid through thermal means to create the fuel additive. Thefuel additive is operable to enhance combustion when placed into contactwith fuel in a combustion zone and combusted. Enhanced combustion meansthat fuel efficiency is increased when compared to fuel without the fueladditive, or that pollutant output in an exhaust gas from the combustionis decreased or a combination of these effects. Typical pollutants caninclude NOx, particulate matter, carbon monoxide and other recognizedpollutants resulting from the combustion of hydrocarbon fuel. It isnoted that different geographical areas focus on minimizing a particularpollutant depending on air characteristics. Reduction of a targetpollutant or a combination of pollutants is highly advantageous.Alternately, increased fuel efficiency results in a total lower volumeof pollutants, as well as economic advantage.

Another preferred embodiment of the phosphorus-containing parentsolution includes the addition of [NH₄]₂HPO₄ to the [Y]_(x)H₂PO₄,[Y]_(x+1)HPO4, and water. Yet another embodiment includes the additionof NH₄C₂H₃O₂ where C₂H₃O₂ ⁻ ion is an acetate group such that thesolution contains [Y]_(x)H₂PO₄, [Y]_(x+1)HPO4, [NH₄]₂HPO₄, NH₄C2H3O2 andwater. When the fuel additive is prepared using ammonium compounds,ammonium compounds being defined as those compounds containing NH_(x)groups, the nitrogen in the solution is essentially all in the form ofammonium ions. There is at most a negligible amount of free ammonia. Ina preferred embodiment, the solution has a pH between about 6.0 and 8.0.

Another preferred embodiment of the phosphorus-containing parentsolution includes the addition of [Y]_(x)PO₄ to the [Y]_(x)H₂PO₄, and[Y]_(x+1)HPO4.

While orthophosphoric acids have been described, also called phosphoricacids, this includes pyrophosphoric acids, which are the condensedanalogs of orthophosphoric acid. The difference being that, through theprocess to condense the orthophosphoric acid. the PO₄ ³⁻ become P₂O₇ ²⁻or other condensed phosphates. Therefore, [Y]_(x)H₂PO₄, and[Y]_(x+1)HPO4 are precursors to pyrophosphoric acids. The use of thepyrophosphoric and other condensed forms is therefore encompassed withinthe definition of the orthophosphate form.

The phosphorus-containing parent solution of one embodiment of theinvention can be used in any type of environment, such as aqueous orhydrophilic environments. In the case of a hydrophilic environment, itis advantageous that the carrier fluid be selected to allow for properdispersion. A dispersant to promote dispersion in the carrier fluid tocreate the fuel additive is also encompassed in a preferred embodiment.For liquid hydrocarbon fuel applications, at least one carrier fluid canpreferably be a hydrophilic fluid that is highly miscible with the fuel.

The fuel additive of the invention is useful to enhance combustion suchthat more complete combustion is achieved with increased combustion toCO₂ and H₂O as compared to the combustion of the fuel without the fueladditive. The outcome is the reduction of products of partial combustionas well as NO_(x), thereby increasing fuel efficiency.

The fuel additive is used by adding this additive to the fuel in anamount sufficient to increase fuel efficiency or to reduce pollutants.The terms enhanced and enhanced combustion refer to either of theseeffects. An example of reduced pollutants is a reduction of NOx in anexhaust gas produced from a combustion zone. Advantageously, both ofthese effects are observed though the addition of the fuel additive ofthe current invention. A preferred embodiment includes the addition ofbetween about 50 and 150 ppm phosphorus into the fuel though theaddition of the fuel additive. Increased amounts of phosphorus areeffective as well. It is notable that a very cost-effective solution canbe prepared with low weight percent of phosphorus. Another preferredtarget is around 1 ppm phosphorus to 150 ppm phosphorus. Positive testresults have been generated as low as 0.25 ppm phosphorus.

Included in the invention is a process for enhancing fuel performance ofa hydrocarbon fuel in a combustion system including the steps ofproviding the fuel additive described above in an amount effective toenhance fuel performance to the hydrocarbon fuel and combusting thehydrocarbon fuel with the fuel additive. The combustion system can beany means known to those with ordinary skill in the art for combustinghydrocarbon. The combustion system can include one or more combustionzones. In a preferred embodiment, this process is used with a liquidhydrocarbon fuel. Similarly, the additive can be used with a solidhydrocarbon fuel. The result of adding the additive to the hydrocarbonfuel is an enhanced fuel that has a substantial amount of hydrocarbonfuel suitable for combustion, and an amount of the fuel additiveoperable to enhance combustion. Preferably, the enhanced fuel containsphosphorus in an amount operable to reduce emissions upon combustion ofthe enhanced fuel as compared to the combustion of the hydrocarbon fuelwithout the fuel additive. More preferably, the enhanced fuel containsphosphorus of between about 1 and 150 ppm by weight.

An alternate embodiment of the invention includes a process forenhancing fuel performance of a hydrocarbon fuel in a combustion systemincluding the steps of adding a chemical addition composition to thehydrocarbon fuel in an amount effective to enhance fuel performance. Thechemical addition composition is created by creating an intermediatesolution by (i) mixing in an aqueous medium a source of reactive NH₂groups with one of the following:

(a) an alkali metal hydroxide to raise the pH of the intermediatesolution above 12 to form an aqueous ammonium/alkali metal hydroxide; or

(b) a source of phosphoric acid to lower the pH of the intermediatesolution to about 0 to form an acidic ammonium mixture.

The next step includes either combining the intermediate solution ofstep (i.a.) with the source of phosphoric acid; or the intermediatesolution of (i.b.) with the hydroxide at a rate sufficient to create ahighly exothermic reaction. This results in reactive NH₂ groups beingcontained in solution during the formation of the chemical additioncomposition. This chemical addition composition is added to thehydrocarbon fuel.

The parent solution or the chemical addition composition of theinvention can be added into or include a combustion fuel. Again, it canbe advantageous to include dispersants to promote dispersion in fuelsthat are hydrocarbon based. Exemplary fuels include gasoline and dieselfuel.

An enhanced fuel is created when a substantial amount of a fuel suitablefor combustion is combined with an amount of the phosphorus-containingparent solution or the chemical addition composition sufficient toreduce emissions or to increase efficiency upon combustion of theenhanced fuel. In certain circumstances, the carrier fluid is a quantityof a target fluid, that is, a fluid that contains the desired fuel.

A composition of phosphoric acid, alkali metal hydroxide and a source ofreactive NH₂ groups has been explored in U.S. Pat. No. 5,540,788 for thecreation of a conversion surface, the disclosure of the patent beingincorporated herein by reference. The current invention includes the useof the conversion surface composition as a fuel additive. In oneembodiment the fuel additive is chemical addition composition for theenhancement of hydrocarbon fuels where the chemical addition compositionhas the composition disclosed in U.S. Pat. No. 5,540,788. Thisembodiment is unique in the use of the source of reactive NH₂ groups,which can be advantageous under certain circumstances. While thechemical composition including reactive NH₂ groups has certainadvantages, it can result in the presence of free ammonia. Various otherembodiments of the fuel additive of this invention avoid the productionof free ammonia and the related issues.

DETAILED DESCRIPTION

The fuel additive of the invention is believed to perform a gas phaseconversion of hydrocarbon fuels to achieve more complete combustion toCO₂ and H₂O in the process. Preferably, the fuel additive is provided asa dispersion in carrier fluid. Preparation preferably includes formingthe aqueous parent solution that is emulsified and then added into baseoils. Dispersion can be aided through the use of emulsifiers anddispersants. In a preferred embodiment, a dispersant with a total basenumber of from 30 to 160 on an oil-free basis is used. Tests run usinginfrared and other testing techniques confirm the reduction of CO fromthe offgas from the combustion of hydrocarbon fuels with the fueladditive of the invention.

Both the new composition disclosed herein and the previously describedcomposition of Defalco can be used to produce the enhanced fuelperformance.

The invention includes the use of the fuel additive in the combustionchamber of an engine. This is believed to be particularly valuable foruse in diesel engines. Use in the engine appears to provide combustionbenefits allowing for a reduction in particulate and other emissions.The process of the invention is effective at the high temperaturesproduced as part of the combustion process such that the fuel additivecan be placed in contact with the metal parts while the engine isrunning at the high temperature produced by the heat of the combustionprocess.

Testing indicates that use of the fuel additive in fuel providesprotection in that the engine heat is reduced. It is presumed that thisis the result of an insulating effect. Also, oxygen radicals areincreased. An increase in efficiency is observed. This increase inefficiency can be the result of a catalytic effect during combustion.

One example of a preferred formulation of the invention includes thefollowing ratios: 1.597 mols KH₂PO₄, 0.693 mol K₂HPO₄, 0.315 mol[NH₄]₂HPO₄ and water. The pH of the solution can be controlled throughmanipulation of the ratios of these components. By manipulating theratios of the resulting H₂PO₄ ⁻ and HPO₄ ²⁻ ions, the solution can becreated in a preferred pH range of about 6.0 to about 8.0.

In a preferred embodiment, KH₂PO₄, K₂HPO₄, [NH₄]₂HPO₄ and water arecreated into the phosphorus containing parent solution that is added toa carrier fluid, such as a refined oil carrier fluid, and mixed withdispersants. Exemplary dispersants include TFA 4690C, polyalkenylsuccinimides, and Oronite ODA 78012 by Chevron or Ethyl Hitec 646 byEthyl Corporation, Richmond Va. Exemplary carrier fluids includepolyoxpropylene monol and polyols, polyoxybutylene monols and polyols,Actaclear ND17 by Bayer, Pittsburg, Pa., and the like. The phosphoruscontaining parent solution is added in at approximately 10 wt. % of therefined oil carrier fluid. This is heated to drive off a significantamount of the solvent, in this case, water. The mixture can be describedat this point as a colloid. When the resulting solution is mixed intothe fuel, an effective amount of the phosphorus in the solution can bedilute. One example of a preferred embodiment is 0.3 wt % phosphorus inthe solution. Upon addition to the fuel, the phosphorus content can bein the range of 5-100 ppb and still be effective. Preferably, 1-250 ppmphosphorus is used in the fuel. Higher amounts are also effective. Morepreferably, 1-150 ppm phosphorus by weight is in the fuel with the fueladditive.

An example of an alternate embodiment of the phosphorus-containingparent solution that is for use in fuel includes mixing about 2.6 molar(M) orthophosphate with alkali metal and ammonium cations, the resultingaqueous parent solution having a pH of 7 at ambient temperatures. Ameasured volume of this aqueous parent solution is suspended in amixture of refined oil carrier fluid and dispersant, most of the waterof the aqueous parent solution is removed thermally, and diluted toabout 0.3 weight % P. This mixture is used, with further dilution, as anadditive to fuels. The dilution is preferably achieved with the samerefined oil carrier fluid. A Group II base oil is preferred. Otherpreferred carrier fluids include light hydrocarbons, gasoline, polygas,kerosene, diesel, naphtha light oils, Group I, III, IV, V or VI baseoils as defined by API, aromatic oils, polybutenes, polyglycols, heavieroils or combinations of the same. The aqueous parent solution preparedin this fashion, when added to fuel, acts is to diminished emission ofpollutant molecules under normal engine operating conditions. An exampleof an alternate embodiment includes the use of phosphoric acid,potassium hydroxide, ammonium hydroxide in water. Acetic acid can alsobe added. The amounts of the components can be adjusted to reach thedesired pH.

EXAMPLE 1

-   1. Prepare a Phosphoric Acid/Acetic Acid solution [H₃PO₄/HOA_(c)    Solution]. For this run, the H₃PO₄/HOA_(c) Solution is about 90%    mole of H₃PO₄ and 10% mole of HOA_(c).-   2. Prepare for reaction De-ionized water-   3. 2,736.39 lbs of the Potassium Hydroxide is added to the water-   4. Add to this aqueous solution 1315.14 lbs of the Ammonium    Hydroxide (29%)-   5. Into the resulting solution, add the H₃PO₄/HOA_(c) Solution and    allow for reaction.-   6. After reaction, adjust pH with acetic acid to a pH of about 7.0.    The resulting product of this reaction is useful as the chemical    addition component to enhance hydrocarbon fuel.

EXAMPLE 2

Laboratory tests with the fuel additive of KH₂PO₄, K₂HPO₄, [NH₄]₂HPO₄ inrefined oil carrier fluid as an additive in diesel fuels show majorimprovements in fuel efficiency. Sodium has also been evaluated for useas a cation in this formulation. Group IA metals are also preferredcations. Factors related to selection of the cation include commercialexpense and corrosion resistance.

EXAMPLE 3

Use of the fuel additive described in Example 2 in combination with alow sulfur diesel fuel provided a 74% reduction in CO emissions in theexhaust gas as compared to diesel without the fuel additive, 34%reduction in SO2, and 55% reduction in particulates.

EXAMPLE 4

Use of the fuel additive described above in combination with natural gasshowed an 87% reduction in the formation of carbon monoxide as comparedto combustion of the natural gas without the fuel additive, and an 18%reduction in NOx.

EXAMPLE 5

Unit Ratio Component lbs weight Phosphoric Acid 2,583 0.25 PotassiumHydroxide 2,736 0.26 Ammonium Hydroxide 1,315 0.13 Acetic Acid 672 0.06Deionized Water 3,105 0.30 Total Phosphorus-Containing Parent Solution10,411 1.00

EXAMPLE 6

Input Unit Ratio Component Lbs weight Star 4 Base Oil 8,544 0.79Kerosene 1,282 0.12 ODA 78012 205 0.02 Hitec 646 205 0.02 Actaclear ND17 85 0.01 Phosphorus-Containing Parent Solution (Example 5) 273 0.03Total 10,748 1.00This is further diluted in base oil to adjust to desired concentrationof phosphorus in fuel additive. The solvent is removed from the solutionin order to create the fuel additive. In this case, the solvent is waterand dehydration is accomplished thermally.

An alternate embodiment includes the use of [NH₄]H₂PO₄, [NH₄]₂HPO₄ andwater.

In a preferred embodiment, the solvent is one that is defined bysolubility or dispersability of the salts in the solvent as well as thevolatility of the solvent. For example, the salts are preferablydispersed throughout the solvent but the solvent is of such volatilitythat it can be boiled out of solution and preferably recovered for reusewithout affecting the resulting product.

While the invention has been shown or described in only some of itsforms, it should be apparent to those skilled in the art that it is notso limited, but is susceptible to various changes without departing fromthe scope of the invention. For example, introduction of the salts intothe fuel or the carrier fluid can be accomplished through speed shearmixing without the creation of an intermediate solution and thesubsequent thermal removal of the solvent. Regarding the salts,[Y]_(x)H₂PO₄, [Y]_(x+1)HPO4 also encompasses [Y]_(x)[H₂PO₄]_(z),[Y]_(x+1)[HPO₄]_(z) where x and z are variable integers.

1. A fuel additive comprising a phosphorus-containing parent solutionand a carrier fluid, the phosphorus-containing parent solutioncomprising a mixture of salts, the mixture of salts comprising:[Y]_(x)H₂PO₄; and [Y]_(x+1)HPO₄, wherein [Y] is a cation, wherein x isan integer, the carrier fluid being operable to maintain the saltswithin the carrier fluid in at least a partially dispersed state, thefuel additive being operable to enhance combustion when placed intocontact with fuel in a combustion zone and combusted, the enhancedcombustion being measurable by increased fuel efficiency or decreasedpollutant output in an exhaust gas resulting from the combustion of thefuel and the fuel additive, wherein the fuel additive is essentiallyfree of alcohol.
 2. The fuel additive of claim 1 further comprising[NH₄]₂HPO₄.
 3. The fuel additive of claim 2 further comprising NH₄C₂H₃O₂where C₂H₃O₂ is an acetate group.
 4. The fuel additive of claim 1wherein the pH of the phosphorus-containing parent solution is betweenabout 6.0 and 8.0.
 5. A process for enhancing fuel performance of ahydrocarbon fuel in a combustion system having a combustion zonecomprising the steps of providing the fuel additive of claim 1 in anamount effective to enhance fuel performance to the combustion zone andcombusting the hydrocarbon fuel with the fuel additive.
 6. The processof enhancing fuel performance of claim 5 wherein the hydrocarbon fuel isa liquid hydrocarbon fuel.
 7. The process of enhancing fuel performanceof claim 5 wherein the hydrocarbon fuel is a solid hydrocarbon fuel. 8.An enhanced fuel comprising a substantial amount of hydrocarbon fuelsuitable for combustion, and an amount of fuel additive of claim 1operable to enhance combustion.
 9. The enhanced fuel of claim 8 whereinphosphorus is present in the hydrocarbon fuel in an amount of betweenabout 1 and 150 ppm by weight.
 10. The enhanced fuel of claim 8 whereinthe amount of fuel additive is the amount operable to reduce emissionsupon combustion of the enhanced fuel as compared to the combustion ofthe hydrocarbon fuel without the fuel additive.
 11. (canceled) 12.(canceled)
 13. A process for creating a fuel additive for enhancingcombustion of a hydrocarbon fuel, the process comprising the steps of:Mixing the salts [Y]_(x)H₂PO₄ and [Y]_(x+1)HPO₄, wherein [Y] is acation, wherein x is an integer, in a solvent to at least partiallydisperse the salts in the solvent to create a phosphorus-containingparent solution; Mixing the phosphorus-containing parent solution with acarrier fluid such that the phosphorus-containing parent solution isgenerally dispersed in the carrier fluid; Removing a substantial portionof the solvent from the mixture of the phosphorus-containing parentsolution with the carrier fluid to create a fuel additive that isoperable to enhance combustion when added to a combustion zone in thepresence of a hydrocarbon fuel and combusted, wherein the fuel additiveis essentially free of alcohol.